HBO’s decidedly adult animated comedy series ventures into the nether regions of Earth’s least inhabitable environment, New York City, which is home to a motley crew of downtrodden creatures. Whether it’s lovelorn rats, gender-questioning pigeons or aging bedbugs in the midst of a midlife crisis, the awkward small talk, moral ambiguity and existential woes of non-human urbanites prove remarkably similar to those of humans. Created by Phil Matarese and Mike Luciano — who voice many of the characters — and produced by Jay and Mark Duplass (“Togetherness”), the series features such guest voiceover artists as Eric Andre, Jessica Chastain, Rob Corddry, Horatio Sanz, Molly Shannon, Ellie Kemper, Marc Maron, Wanda Sykes, Cobie Smulders and Jon Lovitz.